1. Field of the Invention
The present invention relates to an intravascular flow modifier and reinforcement device, i.e., a stent, for use within a body vessel, and more particularly, to a stent for use in combination with vasoocclusive devices placed adjacent to an aneurysm for the purpose of occluding the aneurysm and providing reinforcement for the area of the blood vessel in the vicinity of the aneurysm.
2. Description of Related Art
The progress of the medical arts related to treatment of vascular malformations has dramatically improved with the availability of intravascular devices capable of operating entirely within the vasculature. Thus, many highly invasive surgical procedures and inoperable conditions have been treated by the use of an expanding number of devices and procedures designed for those purposes. One particularly useful development in the medical arts has been the ability to treat defects in relatively small arteries and veins, such as those in the neurovascular system, by use of an infusion catheter and the placement of embolic coils and the like in areas where the malformation is likely to cause or has already caused a rupture in the blood vessel. More specifically, it has been found that the treatment of aneurysms by such devices and procedures allows the medical practitioner to avoid otherwise risky medical procedures. For example, when the defect is located in the brain, a great deal of difficulty is involved in treatment of small defects in the blood vessels with conventional surgical techniques. For these reasons, the progress in development of devices to treat such defects has been encouraged and has produced useful results in a wide variety of patients.
One aspect of these surgical treatments is that an aneurysm or other malformation is symptomatic of a general weakening of the vasculature in the area containing the aneurysm, and mere treatment of the aneurysm does not necessarily prevent a subsequent rupture in the surrounding area of the vessel. Moreover, it is often desirable to provide a means to prevent the migration of the vasoocclusive devices, such as coils and the like, out of the aneurysm in the event that the aneurysm has a relatively large neck to dome ratio.
Stents, which are tubular reinforcements inserted into a blood vessel to provide an open path within the blood vessel, have been widely used in intravascular angioplasty treatment of occluded cardiac arteries. In such applications, the stent is inserted after an angioplasty procedure or the like in order to prevent restenosis of the artery. In these applications, the stents are often deployed by use of inflatable balloons, or mechanical devices which force the stent open, thereby reinforcing the artery wall and provide a clear through-path in the center of the artery after the angioplasty procedure to prevent restenosis.
While such procedures may be useful in certain aspects of vascular surgery in which vasoocclusive devices are used, the weakness of the vasculature and the tortuosity of the neurovasculature places limits on the applicability of such stents in procedures to repair neurovascular aneurysms. Furthermore, the use of placement techniques, such as balloons or mechanical expansions of the type often found to be useful in cardiac surgery, are relatively less useful in vasoocclusive surgery, particularly when tiny vessels, such as those found in the brain, are to be treated.
Hence, those skilled in the art have recognized a need for a stent compatible with techniques in vasoocclusive treatment of aneurysms that provides selective reinforcement in the vicinity of the aneurysm, while avoiding any unnecessary trauma or risk of rupture to the blood vessel. The need for a highly flexible stent with structural integrity that both allows for placement without a balloon or mechanical expansion and provides sufficient radial support for weakened arterial walls when in a deployed state has also been recognized. It would also be desirable to have a stent which allowed placement of embolic coils in the aneurysm after the placement of the stent, but which can retain coils placed both before and after the stent is inserted. The present invention provides these and other advantages.